Are Day/Night power plans worth it in NZ?
A plan splits your into two: a higher daytime rate (typically 35-45 cents) and a much lower overnight rate (typically 18-25 cents). The night window is most commonly 11pm to 7am.
From 1 July 2026 the Electricity Authority requires every retailer with 5% or more market share (Contact, Genesis, Mercury, Meridian) to offer a or plan. Specialist retailers like Powershop (Get Shifty) and Electric Kiwi (Hour of Power) already do, and Contact has its Good Nights plan with three free hours 9pm to midnight on weekdays. Expect a wider menu of options as the new rule kicks in.
Whether they save you money depends almost entirely on what fraction of your electricity use can be moved into the night window. For most households, that fraction is bigger than they think.
Who already uses electricity overnight
Even if you have never deliberately shifted anything, a chunk of your bill is already happening at night:
- Hot water cylinder on . Most NZ cylinders are wired to a small relay that listens for a signal from the lines company and switches the heating element on overnight when the grid has cheap generation to spare. If you have an electric cylinder, ask your lines company (the one named on your bill, e.g. Vector, Orion, Wellington Electricity) whether yours is on ripple. If yes, most of your hot-water heating is already happening overnight.
- Fridge, freezer, router, NAS, standby power. Always on, so they consume the same amount overnight as during the day. On a Day/Night plan all of that 24-hour load is billed at the day rate during the day and the night rate at night, so roughly 30% of always-on consumption shifts to the cheaper rate automatically.
- EV charging. If you plug in when you get home and let it charge through the night, almost all of an EV's load lands in the cheap window.
What you can shift if you try
- Dishwasher: most modern units have a delay-start of 1-24 hours. Load it after dinner, set it for midnight.
- Washing machine: same trick. The clothes in the drum will be fine until morning.
- Pool pump: schedule the pump to run overnight rather than during the day. This single change can save a lot if you have a pool.
- Underfloor heating with a slab: slabs hold heat for hours. Run the element overnight, ride out the day on stored thermal mass.
Things you cannot easily shift include cooking, evening lighting, TV/PC, and the bulk of your heat-pump heating. These will always be billed at the day rate.
Doing the maths
A typical NZ household uses 580 kWh a month. On a flat rate of 40c/kWh, that is $232 in variable charges. Now split that into day vs night usage on a Day/Night plan with 45c day, 24c night:
- No shifting effort, average household: about 25% of consumption already lands at night (always-on appliances + cylinder). 145 kWh at 24c + 435 kWh at 45c = $230.55. Roughly identical. The plan does not help if you do nothing.
- Cylinder confirmed on ripple, average household: about 35% lands at night (140 kWh hot water + 60 kWh always-on). 200 kWh at 24c + 380 kWh at 45c = $219.00. Saves $13/month.
- Cylinder on ripple + dishwasher and washing shifted to night + EV charging 50 kWh/month: about 50% at night. 290 kWh at 24c + 290 kWh at 45c = $200.10. Saves $32/month, $384/year.
The break-even point is roughly 30-35% of consumption shifted to the night window. Below that you might be marginally worse off than a flat-rate plan; above that you save real money.
Laid out as a table, the same 580 kWh/month household looks like this. The flat-rate column is 580 kWh at 40c = $232; the Day/Night columns use 45c day and 24c night:
| Household | Night share | Day/Night bill | vs flat $232 |
|---|---|---|---|
| No shifting | 25% | $230.55 | -$1.45 |
| Cylinder on ripple | 35% | $219.00 | -$13.00 |
| Ripple + laundry shifted | 42% | $210.50 | -$21.50 |
| Ripple + laundry + EV | 50% | $200.10 | -$31.90 |
The pattern is clear: every extra slice of load you push past 11pm is worth roughly 21 cents per kWh (the 45c-to-24c gap). Shift 100 kWh a month and you save about $21; shift 200 kWh and you save about $42. That is the economics of a Day/Night plan in one sentence.
How the rates and savings vary by region
The day-versus-night gap is fairly consistent across NZ retailers - night is usually around 60% of the day rate wherever you are. What changes is the size of the bill that gap is applied to, because the underlying flat rate differs sharply by lines area. A household in a high-rate region simply has more dollars on the table to shift:
- Wellington (lower-rate): shifting 200 kWh/month to night saves around $19/month.
- Auckland (mid-rate): the same shift saves around $21/month.
- Dunedin and the southern lines areas (higher-rate): the same shift saves around $24-27/month.
So the further south and the higher your flat rate, the more a Day/Night plan rewards the effort of moving load overnight. Always confirm the actual numbers for your address on Powerswitch - regional retail offers move around quarter to quarter.
Things to check before switching
- Is your cylinder actually on ripple? If not, switching to a Day/Night plan and not changing anything else will save very little. Some older homes have continuous-supply hot water that runs whenever the thermostat asks for heat.
- Does the retailer's "night" window suit you? 11pm-7am is the most common, but a few retailers offer 9pm-7am which is much more useful for evening dishwasher and laundry loads.
- Does the plan have a higher fixed daily charge? Some Day/Night plans bake the convenience into a slightly higher fixed cost. Compare on Powerswitch.
- Free hours of power. Several retailers (Electric Kiwi's Hour of Power, others) offer one free hour off-peak instead of a Day/Night structure. For some households that is simpler and saves more.
What to do next
A sensible order of operations before you commit to a plan switch:
- Confirm your cylinder is on ripple. Phone the lines company named on your bill and ask. This single fact decides whether a Day/Night plan is worth it for most households. The hot water cylinder is the biggest shiftable load in a typical NZ home.
- List what else you can move. The dishwasher and washing machine almost always have a delay-start. An EV charger can be scheduled. Add up the monthly kWh those represent.
- Multiply by the gap. Take that monthly figure and multiply by about 21 cents - the typical day-to-night price difference. If the answer clears $15-20/month you are almost certainly better off switching.
- Compare offers on Powerswitch and watch the fixed daily charge as well as the unit rates, then make the switch.
Try it in the calculator
The NZ Power Bill Calculator supports separate day and night rates. Open the "Override rates" panel in Section I, enter your retailer's rates, and choose which appliances bill at the night rate. Hot-water cylinders and hot-water heat pumps default to night-rate billing, which is usually correct for ripple-controlled NZ homes.
Related guides
- EV home charging cost in NZ - overnight charging on a Day/Night plan significantly cuts per-km cost
- Average NZ power bill by region (2026) - regional context for whether plan savings are significant
- The most expensive appliances in NZ homes - knowing your biggest loads tells you what is worth shifting